Printer with plurality of paper receiving trays and paper discharge control method for 
the same

ABSTRACT

A printer including: a plurality of paper receiving trays configured to receive discharged sheets; a tray full detection sensor configured to detect that an amount of discharged sheets stacked on the respective paper receiving trays reaches a respective predetermined amount; a tray empty detection sensor configured to detect that no discharged sheets are stacked on the respective paper receiving trays; and a paper discharge control unit configured to, when the tray full detection sensor detects that an amount of discharged sheets stacked on a first paper receiving tray used as a current paper discharge destination reaches the predetermined amount during printing, perform continuous paper discharge to continue printing by changing the paper discharge destination from the first paper receiving tray to a second paper receiving tray that the tray empty detection sensor detects as having no discharged sheets stacked thereon at a time of the detection of the first paper receiving tray and that receives discharged sheets with printed surfaces facing a same direction as that of the first paper receiving tray.

CROSS REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2008-212001, filed on Aug. 20, 2008, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a printer including multiple paper receiving trays and a paper discharge control method for the same.

2. Description of the Related Art

A printer with multiple paper receiving trays described in Japanese Patent Application Publication No. 2003-326810 is configured to continue printing even when one of the paper receiving trays serving as a paper discharge destination and currently receiving discharged sheets becomes full of discharged sheets, by causing another paper receiving tray to take over the receiving of discharged sheets.

SUMMARY OF THE INVENTION

Generally, paper receiving trays include a face-up paper receiving tray in which sheets of paper are stacked with printed surfaces facing up and a face-down paper receiving tray in which sheets of paper are stacked with printed surfaces facing down. Accordingly, only changing the paper discharge destination from one paper receiving tray to another may cause inconsistency in the order of pages. To avoid such a situation, in Japanese Patent Application Publication No. 2003-326810, the order of printing is modified before the paper receiving trays are changed. However, the control for such modification is complicated. Moreover, conventional printers have been designed without consideration of reusing a paper receiving tray as a paper discharge destination after the paper receiving tray is once full of discharged sheets.

An object of the present invention is to provide a printer including multiple paper receiving trays which is capable of implementing simple control of paper discharge, and of reusing as a paper discharge destination a paper receiving tray once full of discharged sheets, and to provide a paper discharge control method for the printer.

To achieve the above object, a first aspect of the present invention is a printer comprising: a plurality of paper receiving trays configured to receive discharged sheets; a tray full detection sensor configured to detect that an amount of discharged sheets stacked on the respective paper receiving trays reaches a respective predetermined amount; a tray empty detection sensor configured to detect that no discharged sheets are stacked on the respective paper receiving trays; and a paper discharge control unit configured to, when the tray full detection sensor detects that an amount of discharged sheets stacked on a first paper receiving tray used as a current paper discharge destination reaches the predetermined amount during printing, perform continuous paper discharge to continue printing by changing the paper discharge destination from the first paper receiving tray to a second paper receiving tray that the tray empty detection sensor detects as having no discharged sheets stacked thereon at a time of the detection of the first paper receiving tray and that receives discharged sheets with printed surfaces facing a same direction as that of the first paper receiving tray.

According to the first aspect, when the paper receiving tray used as the paper discharge destination becomes full, the paper discharge destination is changed to another paper receiving tray configured to accommodate discharged sheets with the printed surfaces facing the same direction as those of the paper receiving tray used as the current paper discharge destination. This eliminates the need to modify the printing order for changing the paper receiving trays and simplifies the control of paper discharge. Moreover, the paper discharge destination is changed to a paper receiving tray that is detected as a paper receiving tray having no discharged sheets thereon upon detection that a paper receiving tray currently set as the paper discharge destination is full. Accordingly, by removing the discharged sheets from the paper receiving tray which is full of discharged sheets, the paper receiving tray which is once full of discharged sheets can be used again as the paper discharge destination.

The paper discharge control unit may temporarily stop printing without changing the paper discharge destination when the second paper receiving tray does not exist.

The printer may further comprise a print setting acquisition unit configured to acquire a print setting including a setting of a paper discharge destination and a selection as to whether or not to perform continuous paper discharge, and the paper discharge control unit may determine, as a paper discharge destination at start of printing, a paper receiving tray belonging to a group having a larger number of paper receiving trays that receive discharged sheets with printed surfaces facing a same direction, when the print setting acquired by the print setting acquisition unit indicates that no paper receiving tray is set as a paper discharge destination and that performance of continuous paper discharge is selected.

According to the aforementioned configuration, if a first one of the paper receiving trays set as the paper discharge destination becomes full of discharged sheets, the paper discharge is taken over by another paper receiving tray configured to accommodate discharged sheets with the printed surfaces facing the same direction as those of the first paper receiving tray. Accordingly, as the number of paper receiving trays configured to accommodate discharged sheets with the printed surfaces facing the same direction increases, the possibility of continuing the paper discharge becomes higher.

The paper discharge control unit may perform continuous paper discharge to continue printing by changing the paper discharge destination from the second paper receiving tray to the first paper receiving tray when the tray full detection sensor detects that an amount of discharged sheets stacked on the second paper receiving tray used as a current paper discharge destination reaches the predetermined amount and also when the tray empty detection sensor detects that no discharged sheets are stacked on the first paper receiving tray at a time of the detection of the second paper receiving tray during printing after the paper discharge control unit changes the paper discharge destination from the first paper receiving tray to the second paper receiving tray.

To achieve the above object, a second aspect of the present invention is a method for controlling paper discharge in a printer including a plurality of paper receiving trays, the method comprising: detecting that an amount of discharged sheets stacked on a first one of the paper receiving trays used as a paper discharge destination reaches a predetermined amount during printing; and performing continuous paper discharge to continue printing by changing the paper discharge destination to a second one of the paper receiving trays that is detected as having no discharged sheet stacked thereon at the time of the detection of the first paper receiving tray and is configured to have discharged sheets stacked with printed surfaces facing the same direction as that of the first paper receiving tray.

According to the second aspect, it is possible to obtain the same effects as those of the first aspect.

The method for controlling paper discharge may further comprise temporarily stopping printing without changing the paper discharge destination when the second paper receiving tray does not exist.

The method for controlling paper discharge may further comprise: acquiring a print setting including a setting of a paper discharge destination and a selection as to whether or not to perform continuous paper discharge, before starting printing; and determining, as a paper discharge destination at start of printing, a paper receiving tray belonging to a group having a larger number of paper receiving trays that receive discharged sheets with printed surfaces facing a same direction, when the acquired print setting indicates that no paper receiving tray is set as a paper discharge destination and that performance of continuous paper discharge is selected.

The method for controlling paper discharge may further comprise performing continuous paper discharge to continue printing by changing the paper discharge destination from the second paper receiving tray to the first paper receiving tray when detecting that an amount of discharged sheets stacked on the second receiving tray used as a current paper discharge destination reaches the predetermined amount and also when detecting that no discharged sheets are stacked on the first paper receiving tray at a time of the detection of the second paper receiving tray during printing after changing the paper discharge destination from the first paper receiving tray to the second paper receiving tray.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an example of a configuration of a print system including a printer according to an embodiment of the present invention.

FIG. 2 is a view showing a paper feed unit, paper receiving trays, and print sheet transfer paths of the printer according to the embodiment of the present invention.

FIG. 3 is a block diagram showing a functional configuration of the printer according to the embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a paper discharge controller of the printer according to the embodiment of the present invention.

FIG. 5 is a view showing an example of a printing condition setting screen used when the paper discharge destination is set from a printer driver of a PC.

FIG. 6 is a view illustrating a paper discharge destination selection menu.

FIG. 7 is a view showing an example of a printing condition setting screen used when the paper discharge destination is set from the printer according to the embodiment of the present invention.

FIG. 8 is a flowchart illustrating paper discharge control, during execution of printing, by the printer according to the embodiment of the present invention.

FIG. 9 is a flowchart illustrating a paper discharge destination setting process of the printer according to the embodiment of the present invention.

FIGS. 10( a) to 10(e) are views schematically showing setting of the paper discharge destination performed on the printer according to the embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENT

Hereinafter, a description is given of an embodiment of the present invention with reference to the drawings. FIG. 1 is a block diagram showing an example of the configuration of a print system according to the embodiment. As shown in FIG. 1, the print system includes a printer 10 and a personal computer (PC) 20 functioning as a print controller. The connecting form of the printer 10 and PC 20 is typically a local area network (LAN) connection in which the printer 10 is shared by the multiple PCs 20 but may be a local connection in which the printer 10 and PC 20 are connected one to one.

The printer 10 includes multiple paper feeders having different paper feed capacities and multiple paper receiving trays. The printer 10 includes a print function of printing based on print data sent from the PC 20 and a copy function of reading an image of an original placed on a platen and then printing the image for duplication.

In the PC 20, a printer driver program developed for the printer 10 is installed. The printer driver program is executed by the CPU of the printer 20 to configure a printer driver 210. The printer driver 210 is operated to cause the PC 20 to serve as a print controller.

The printer driver 210 performs generates print data of a document or the like to be printed on the basis of an instruction from a user and then performs a process of outputting the data to the printer 10. To perform this process, the printer driver 210 includes a printing condition setter 211 and a print data generator 212. The printing condition setter 211 is configured to receive settings of the printing conditions including print quality, a number of prints, print size, a type of paper, a paper feeder, a paper receiving tray, and the like. The print data generator 212 is configured to generate print data on the basis of a document set to be printed and the settings of the printing conditions received by the printing condition setter 211 and then output the generated print data to the printer 10.

FIG. 2 is a view showing the configuration of paper feed and discharge units and printing units of the printer 10. As shown in FIG. 2, the printer 10 includes as the paper feed units, a paper feed table 320 a, a first paper feed tray 320 b, a second paper feed tray 320 c, a third paper feed tray 320 d, and a fourth paper feed tray 320 e. The printer 10 includes, as the paper discharge units, a face-down paper receiving tray 330 a, a first face-up paper receiving tray 330 b, a second face-up paper receiving tray 330 c, and a third face-up paper receiving tray 330 d.

The printer 10 performs printing on print paper fed from any one of the paper feed units by use of print heads 312 and discharges the paper to any one of the paper receiving trays. The face-down paper receiving tray 330 a is placed on the top surface side of the printer 10 and is located at the position where print paper is half turned with respect to the print heads 312. Accordingly, the printed sheets are discharged to the paper receiving tray 330 a in face-down mode (hereinafter, referred to as face-down mode). The first to third face-up paper receiving trays 330 b to 330 d are disposed on a lateral side of the printer 10 in a direction that paper is transferred during printing (referred to as a transfer direction). The printed sheets of paper are therefore discharged in face-up mode (hereinafter, referred to as face-up mode).

In this embodiment, as described above, the printer 10 includes the single paper receiving tray to which printed sheets are discharged in face-down mode and the three paper receiving trays to which printed sheets are discharged in face-up mode. The printed sheets (discharged sheets) are stacked up on each other in each tray. To obtain a result that the printed surfaces ordered by page number, it is necessary to print the sheets in the logical order of pages in the case of discharge to the paper receiving tray for face-down mode, and in reverse order in the case of discharge to the paper receiving tray for face-up mode. The printer 10 may include multiple the paper receiving trays to which sheets are discharged in face-down mode. Moreover, a post-processing device which performs stapling, punching, and the like may be provided before the face-up paper receiving trays 330 b to 330 d.

The printer 10 includes as the printing units the print heads 312 extending perpendicularly to the paper transfer direction and each having a number of nozzles. The print heads 312 are independently provided corresponding to individual ink colors. Each of the print heads 312 discharges black or color ink to perform color printing line by line.

Moreover, the printer 10 includes: a controller 110 constituted of a controller substrate and the like with a CPU, a memory, and the like arranged thereon and the like; an image reader 130 which reads an image of an original placed on the platen; an operation panel 150 which receives operations from a user; and other functional units (see FIG. 3).

The print sheets fed one by one from any one of the paper feed units are transferred by driving units such as rollers constituting a transfer driver 350 along a paper feed path (indicated by black thick lines in the drawing) within the casing and are guided to a registration section Rg. Herein, the registration section Rg is provided for the purpose of registration of the leading edge of each print sheet and skew correction thereof and is configured by including a pair of registration rollers. Each fed print sheet temporarily stops at the registration section Rg and is transferred towards the printing units at predetermined timing.

The print sheet is transferred at a speed determined according to the printing conditions by an annular transfer belt 352 provided facing the print heads 312 while an image is formed line by line with the ink ejected from the print heads 312.

In the case of paper discharge to the third face-up paper receiving tray 330 d, the print sheets printed on the upper surfaces are transferred by a switching unit 382 toward the third face-up paper receiving tray 330 d and are discharged to be stacked in face-up mode on the third face-up paper receiving tray 330 d. In the case of paper discharge to the second face-up paper receiving tray 330 c, the print sheets printed on the upper surfaces are transferred by a switching unit 383 toward the second face-up paper receiving tray 330 c and are discharged to be stacked in face-up mode on the second face-up paper receiving tray 330 c. In the case of paper discharge to the first face-up paper receiving tray 330 b, the print sheets printed on the upper surfaces thereof are transferred by a switching unit 384 toward the first face-up paper receiving tray 330 b and are discharged to be stacked in face-up mode on the first face-up paper receiving tray 330 b.

In the case of paper discharge to the face-down paper receiving tray 330 a, the print sheets are further transferred in the casing by the driving units such as rollers. The print sheets are guided by a switching unit 386 toward the face-down paper receiving tray 330 a and are discharged to be stacked in face-down mode on the face-down paper receiving tray 330 a.

Each of the paper receiving trays is shaped in a tray protruding from the casing and has a certain thickness. Each paper receiving tray is inclined so that the discharged print sheets slide along the slope to be stacked while being naturally aligned by a wall provided at the lower end of the inclined tray.

In each of the face-down paper receiving tray 330 a and first to third face-up paper receiving trays 330 b to 330 d, a predetermined number of sheets (also referred to as paper discharge capacity) can be stacked. The paper receiving trays 330 a to 330 d are respectively provided with tray full detection sensors 332 a to 332 d detecting that the amounts of discharged sheets stacked thereon reach predetermined amounts around the respective paper capacities (a paper full state). In other words, the paper full state of each paper receiving tray means that the amount of discharged sheets stacked therein reaches the predetermined amount around the paper discharge capacity of the paper receiving tray. Moreover, the paper receiving trays 330 a to 330 d are respectively provided with tray empty detection sensors 334 a to 334 d each of which detects whether or not the paper receiving tray is empty (a paper empty state), that is, no discharged sheets are stacked.

In the case of duplex printing, that is, printing on both sides of each print sheet, after printing on a front surface (a surface on which printing is performed firstly is referred to as a front surface, while a surface on which printing is performed secondly is referred to as a back surface), the printed sheet is further transferred in the casing by the switching unit 386 without being guided to any paper receiving tray. The print sheet is then drawn into a switchback route SR to be switched back. The front and back surfaces of the switched back sheet are inverted with respect to the transfer path. After the inversion, the sheet is again guided to the registration section Rg by the driving units such as rollers and is then temporarily stopped. Thereafter, the sheet is transferred to the printing unit at the predetermined timing.

In the case of duplex printing, printing on the back surface is performed by a procedure similar to the case of printing on the front surface. The print sheet with images formed on the both sides are discharged and stacked in any one of the paper receiving trays according to the specified paper discharge destination included in the printing condition.

In the printer 10, the switchback for reversing the sheets is designed to be performed using space provided within the face-down paper receiving tray 330 a. The space provided within the face-down paper receiving tray 330 a is closed so that the print sheets cannot be taken out from the outside during the switchback operation. This can prevent the user from pulling out print sheets which are being switched back. Moreover, since the face-down paper receiving tray 330 a is originally provided to the printer 10, the switchbacking within the space provided in the face-down paper receiving tray 330 a eliminates the need to provide another space for switchback. This can prevent the casing from increasing in size. Furthermore, the face-down paper receiving tray 330 a is not shared with the switchback route. Accordingly, the switchback process and discharge of other sheets can be performed in parallel.

FIG. 3 is a block diagram showing a functional configuration of the printer 10 of this embodiment. As shown in FIG. 3, the printer 10 includes the controller 110, a communication processer 120, the image reader 130, the operation panel 150, a print executer 310, a paper feeder 320, a paper discharger 330, and a transfer driver 350.

To allow communication with the PC 20, the communication processor 120 performs protocol processing suitable for the connection form. For example, in the case of the LAN connection, the communication processor 120 performs communication processing by TCP/IP. Moreover, the communication processor 120 receives print data as image information from the PC 20 which is one of input sources of the image information.

The image reader 130 is one of the input sources of the image information and includes the platen, a light receiving device, a light source, a lens, a scanner, and the like. The image reader 130 performs processes of: reading image data of an original placed on the platen; converting the image data to an electric signal; and outputting the electric signal to the controller 110 as the image information. The image reader 130 may be provided in the printer 10 or outside the printer 10.

The print executer 310 is configured to perform image formation on a print sheet using an image forming medium. In this embodiment, the print executer 310 employs an ink-jet unit which ejects ink line by line from the print heads 312 having a width covering the print sheet for execution of printing. The image forming medium may be a serial-type ink-jet unit or a laser printing unit using toner or the like.

The paper feeder 320 feeding print sheets includes five paper feed units: the paper feed table 320 a exposed to the outside of the printer 10 as shown in FIG. 2; and the first to fourth paper feed trays 320 b to 320 e which are rack-type and are accommodated within the printer 10. In each of the paper feed units, multiple print sheets can be set in a stacked state. For the print sheets, sizes such as A4 and A5 and paper types such as plain paper and ink-jet print paper are determined. In each paper feed unit, print sheets of a single size and a single paper type are set. Each paper feed unit is provided with a paper feed sensor, which can detect a paper-out condition.

The paper discharger 330 configured to accommodate print sheets which are already printed and discharged includes the multiple paper receiving trays. In this embodiment, the paper discharger 330 includes the face-down paper receiving tray 330 a and first to third face-up paper receiving trays 330 b to 330 d as shown in FIG. 2.

The paper receiving trays 330 a to 330 d are provided with the tray full detection sensors 332 a to 332 d (see FIG. 2) and the tray empty detection sensors 334 a to 334 d (see FIG. 2), respectively. The tray full detection sensors 332 a to 332 d are configured to detect that the amounts of sheets discharged and stacked in the paper receiving trays 330 a to 330 d reach the respective predetermined amounts around the tray capacities. The tray empty detection sensors 334 a to 334 d are configured to detect whether or not the paper receiving trays 330 a to 330 d are empty, respectively. Each of the tray full detection sensors 332 a to 332 d detects, for example, the weight of the sheets discharged and stacked or the height of the sheets discharged and stacked by reading reflected light, and thereby can judge whether or not the amount of the sheets discharged and stacked reaches the predetermined amount. Alternatively, each of the paper receiving trays 330 a to 330 d counts the number of sheets printed and discharged thereto and thereby can judge whether or not the amount of the sheets discharged and stacked reaches the predetermined amount. Each of the tray empty detection sensors 334 a to 334 d for example reads reflected light and thereby can judge whether or not the paper receiving tray is empty.

The transfer driver 350 is the driving unit transferring print sheets and is constituted of a motor and the like. Moreover, at the position facing the print heads 312, the transfer belt 352 is provided, which functions as the print transfer unit transferring print sheets at a predetermined print transfer speed during printing. Furthermore, in order to guide the print sheets to a paper receiving tray to be used for paper discharge, the transfer driver 350 includes the multiple switching units (see FIG. 2) switching transfer paths.

The controller 110 includes the CPU, memory, image processor, and the like. These devices perform processing to configure an operation panel controller 111, a paper feed controller 113, a paper discharge controller 114, a transfer controller 115, an image processor 116, and an ink ejection processor 117.

The operation panel controller 111 is configured to perform a process of interpreting user's operations inputted through the screens displayed on the operation panel 150 or the operation panel 150. The paper feed controller 113, according to the printing conditions, sets a paper feed unit which supplies print sheets used in printing and performs a control of feeding print sheets from the paper feed unit to the transfer driver 350 at predetermined timing. The paper discharge controller 114, according to the printing conditions, selects a paper receiving tray to which print sheets are discharged among the paper receiving trays 330 a to 330 d and notifies the transfer controller 115 of the selected paper receiving tray so that the print sheets are discharged to the selected paper receiving tray. Moreover, when the paper receiving tray set as the paper discharge destination becomes full of discharged sheets, the paper discharge controller 114 specifies a paper receiving tray which takes over the receiving of discharged sheets among the paper receiving trays 330 a to 330 d if necessary.

The transfer controller 115 controls transfer of print sheets at the transfer driver 350 including the transfer belt 352 and the other driving units. Specifically, the transfer controller 115 sets the transfer speed and path and outputs a control signal to the transfer driver 350 so that transfer of print sheets according to the settings can be performed. The transfer speed is determined by the printing conditions such as the print quality and paper type, and the transfer path is determined by the specified paper feed unit, specified paper receiving tray, duplex print settings, and the like.

The image processor 116 converts RGB print data into CMYK data and further performs a process such as conversion into the data to image data which can be interpreted by the print executor 310. The image data is for example data showing the number of ink drops of each dot. The ink ejection processor 117 controls an ink ejection process of the print heads 312 based on the image data.

FIG. 4 is a block diagram showing a configuration of the paper discharge controller 114 which is a characteristic functional unit of this embodiment. As shown in FIG. 4, the paper discharge controller 114 includes a paper discharge setter 1141, a printing condition acquisition unit 1142, and a paper receiving tray state acquisition unit 1143.

When the setting of the paper discharge destination set by the user is “AUTO,” the paper discharge setter 1141 sets a paper receiving tray to be used as the paper discharge destination. Moreover, when the paper receiving tray in use becomes full of discharged sheets during printing, the paper discharge setter 1141 sets a paper receiving tray which takes over the receiving of discharged sheets if necessary.

Specifically, when later-described continuous paper discharge is set by the user, the paper discharge setter 1141 sets a paper receiving tray whose face direction is the same as that of the paper receiving tray full of discharged sheets and does not have discharged sheets thereon, as the paper discharge destination which takes over the receiving of the discharged sheets.

The printing condition acquisition unit 1142 acquires the setting of the paper discharge destination and the setting related to the continuous paper discharge from the printing conditions set from the PC 20 or operation panel unit 150, and then notifies the paper discharge setter 1141 of the settings. The paper receiving tray state acquisition unit 1143 acquires detection results of the tray full detection sensors 332 a to 332 d and tray empty detection sensors 334 a to 334 d of the paper receiving trays 330 a to 330 d and notifies the paper discharge setter 1141 of the results.

Next, a description is given of a basic procedure of the printing process of the printer 10. As described above, the printer 10 includes a copy function of reading an image and copying the image in addition to the print function of printing based on print data sent from the PC 20. Accordingly, the printing procedure is carried out for a corresponding one of the functions.

Specifically, when the printer 10 receives print data from the PC 20 as the image information, the image processer 116 performs a process of developing the received print data into image data, and the print executor 310 performs the printing process. In this case, the printing conditions are set by the printer driver 210 of the PC 20.

When the printer 10 receives a copy operation from the user through the operation panel 150, the image reader 130 performs a process of reading an image of an original placed on the platen, and the print executor 310 performs the printing process based on the image data as the image read information. In this case, the printing conditions are set by the operation panel 150 and operation panel controller 111.

Next, a description is given of the process of setting the printing conditions when the printer 10 performs printing and especially the process of setting the paper discharge destination. To print with the printer 10, the user can set the printing conditions before printing, including the paper size, paper type, the number of prints, and paper discharge destination. The printing conditions are set from the printer driver 210 of the PC 20 in the case of printing using the print function and are set from the operation panel 150 and operation panel controller 111 of the printer 10 in the case of printing using the copy function.

With reference to FIG. 5, a description is given of the setting of the paper receiving tray (paper discharge destination). FIG. 5 shows an example of a printing condition setting screen 510 in the case where the printing conditions are set from the printer driver 210 of the PC 20. In the printing condition setting screen 510, the setting items are classified into menu pages of “BASIC,” “LAYOUT,” “FINISH,” and the like. In this embodiment, the user can select the paper discharge destination by use of a paper discharge destination selection menu 511 of a pull-down menu on the menu page concerning “FINISH.”

Herein, as shown in FIG. 6, in the pull-down paper discharge destination selection menu 511, in addition to “FACE-DOWN PAPER RECEIVING TRAY,” “FIRST FACE-UP PAPER RECEIVING TRAY,” “SECOND FACE-UP PAPER RECEIVING TRAY,” and “THIRD FACE-UP PAPER RECEIVING TRAY” respectively corresponding to the paper receiving trays 330 a to 330 d provided for the printer 10, “AUTO” can be selected. When the user wants to specify a certain paper receiving tray, the user should select any one of “FACE-DOWN PAPER RECEIVING TRAY,” “FIRST FACE-UP PAPER RECEIVING TRAY,” “SECOND FACE-UP PAPER RECEIVING TRAY,” and “THIRD FACE-UP PAPER RECEIVING TRAY.” If the user allows the printer 10 to select the paper discharge destination, the user should select “AUTO.” Before displaying this menu, the printer driver 210 communicates with the printer 10 and acquires information concerning available paper receiving trays.

Moreover, in a continuous paper discharge setting field 512, the user can set whether to perform continuous paper discharge. Herein, the continuous paper discharge is a paper discharge manner in which when the paper receiving tray in use becomes full of discharged sheets, the paper discharge is taken over by another paper receiving tray having the same face direction as that of the paper receiving tray in use. Here, the face direction is face-up or face-down.

Specifically, in this embodiment, for example, when the first face-up paper receiving tray 330 b which is set to the paper discharge destination becomes full of discharged sheets, the paper discharge can be taken over by any one of the second and third face-up paper receiving trays 330 c and 330 d having the same face direction as that of the first face-up paper receiving tray 330 b. When the paper receiving tray which takes over the paper discharge becomes full of discharged sheets, the paper discharge can be taken over by another paper receiving tray having the same face direction as that of the paper receiving tray in use. If the first face-up paper receiving tray 330 b already gets out of the full state and is empty at this time, the first face-up paper receiving tray 330 b can be used again as the paper discharge destination. The case where a tray gets out of the full state and is empty is for example a case where the user removes discharged sheets from the first face-up paper receiving tray 330 b.

In the case where the continuous paper discharge is set, if the paper receiving tray in use becomes full of discharged sheets, another paper receiving tray which can receive the sheets and has the same face direction takes over the receiving of the discharged sheets, thus allowing continuous printing. In the case where the continuous paper discharge is not set, if the paper receiving tray in use becomes full of discharged sheets, the printing process is temporarily stopped as a paper discharge error. However, even in the case where the continuous paper discharge is set, if there is no other paper receiving tray which can receive discharged sheets and has the same face direction, the paper discharge error occurs, and the printing process is temporarily stopped.

If the user wants to continue printing by allowing another paper receiving tray to receive discharged sheets even when the paper receiving tray in use becomes full of the discharged sheets, the user can set the continuous paper discharge. If the user wants to avoid distribution of the printed results to multiple paper receiving trays when the paper display tray in use becomes full, the user has an option not to set the continuous paper discharge.

The setting whether to execute the continuous paper discharge is applied to both the cases where a certain paper receiving tray is specified and where “AUTO” is selected. In other words, in the continuous paper discharge setting, when the paper receiving tray in use becomes full of discharged sheets, the paper discharge is taken over by another paper receiving tray which can receive the discharged sheets and has the same face direction in both cases where the a certain paper receiving tray is specified and where “AUTO” is selected.

FIG. 7 shows an example of the paper discharge destination setting screen 150 a displayed on the operation panel 150 to set the paper discharge destination from the operation panel 150 of the printer 10 when printing is performed by the copy function (copy printing). In this example, as the paper discharge destination in copy printing, the user can select any one of “FACE-DOWN PAPER RECEIVING TRAY,” “FIRST FACE-UP PAPER RECEIVING TRAY,” “SECOND FACE-UP PAPER RECEIVING TRAY,” and “THIRD FACE-UP PAPER RECEIVING TRAY” from a button group 151. Moreover, the user can specify through a button group 152 whether to perform the continuous paper discharge. The contents of these settings are the same as those in the case of setting the printing conditions from the printer driver 210 of the PC 20.

Next, with reference to the flowchart of FIG. 8, a description is given of paper discharge control of the printer 10 during execution of printing.

Upon receipt of an instruction from the user to execute printing, the printing condition acquisition unit 1142 of the paper discharge controller 114 acquires the printing conditions set by the user, and the paper discharge setter 1141 sets the paper discharge destination based on the printing conditions (S101).

FIG. 9 is a flowchart illustrating details of the process of setting the paper discharge destination. As shown in FIG. 9, in the paper discharge destination setting process, at first, it is judged whether the paper discharge destination set in the printing conditions is “AUTO” (S1011).

The paper discharge destination which is not set to “AUTO” (No in S1011) means that a certain one of the paper receiving trays is specified. Accordingly, the paper discharge destination is set to a certain paper receiving tray specified according to the user's instruction (S1012). Specifically, according to the user's instruction, the paper discharge destination is set to any one of the face-down paper receiving tray 330 a and first to third face-up paper receiving trays 330 b to 330 d.

On the other hand, if the paper discharge destination is set to “AUTO” (Yes in S1011), it is further judged whether “CONTINUOUS PAPER DISCHARGE” is set (S1013). If the “CONTINUOUS PAPER DISCHARGE” is not set (No in S1013), the paper discharge destination is set to the face-down paper receiving tray 330 a (S1014). This is because if sheets are discharged to the face-down paper receiving tray 330 a, the printed sheets arranged according to page number can be obtained by printing in normal order of pages, thus shortening the time taken to start printing.

If the “CONTINUOUS PAPER DISCHARGE” is set (Yes in S1013), the paper discharge destination is set to one of the paper receiving trays belonging to a group having the same face direction and a larger number of paper receiving trays (S1015). Here, in the case where the “CONTINUOUS PAPER DISCHARGE” is set, if the paper receiving tray set as the paper discharge destination becomes full of discharged sheets, the paper discharge is taken over by another one of the paper receiving trays having the same face direction. For this reason, as the number of paper receiving trays in the group having the same face direction and selected as the paper discharge destination increases, the possibility of continuing paper discharge becomes higher. In this embodiment, the numbers of the face-down and face-up paper receiving trays are one and three, respectively. Accordingly, the paper discharge destination is set to any one of the face-up paper receiving trays 330 b to 330 d.

To determine which one of the first to third face-up paper receiving trays 330 b to 330 d should be specified as the paper discharge destination, the priorities thereof are previously determined. For example, the paper receiving trays are prioritized in descending order of maximum paper discharge capacity thereof.

After the paper discharge destination is set, the printing order of pages is set depending on the face direction of the paper discharge destination (S102). Specifically, when the paper discharge destination is set to the face-down paper receiving tray, the printing order is set to the normal order of pages. When the paper discharge destination is set to the face-up paper receiving tray, the printing order is set to the reverse order.

According to the set printing order, the printing process is performed, including paper feed, image formation, and paper discharge (S103). If printing of all pages to be printed is completed (Yes in S104), the printing process is terminated.

If printing is not completed (No in S104), it is judged whether or not the tray full detection sensor (332 a to 332 d) of the paper receiving tray (330 a to 330 d) set as the paper discharge destination detects that the paper receiving tray is full of discharged sheets (S105). If the tray full detection sensor does not detect that the paper receiving tray is full (No in S105), the printing process including the paper feed, image formation, and paper discharge is repeated (S103).

On the other hand, if the tray full detection sensor (332 a to 332 d) of the paper receiving tray (330 a to 330 d) set as the paper discharge destination detects that the paper receiving tray is full of discharged sheets (Yes in S105), it is judged whether or not the “CONTINUOUS PAPER DISCHARGE” is set (S106). If the “CONTINUOUS PAPER DISCHARGE” is not set (No in S106), printing is temporarily stopped as a paper discharge error due to the paper full state (S109). This is because the user does not want the paper discharge to be taken over by another paper discharge destination.

If the “CONTINUOUS PAPER DISCHARGE” is set (Yes in S106), the availability of the paper receiving trays 330 a to 330 d at that time is acquired with reference to the tray empty detection sensors 334 a to 334 d (S107). Specifically, the paper receiving tray which is once full of discharged sheets is judged available if discharged sheets are removed by the user. Accordingly, even the paper receiving tray which is once full of discharge paper can be used again as the paper discharge destination. Herein, the availability may be judged among only the paper receiving trays having the same face direction as that of the paper receiving tray set as the paper discharge destination.

From the obtained availability of the paper receiving trays, it is judged whether or not there is an empty receiving tray having the same face direction as that of the paper discharge destination full of paper (S108). If there is no empty paper receiving tray having the same face direction as that of the paper discharge destination full of paper (No in S108), there is no paper discharge destination which can take over the receiving of discharged sheets, printing is temporarily stopped as the paper discharge error because of the paper receiving tray becomes full (S109).

If there is an empty paper receiving tray having the same face direction (Yes in S108), the paper discharge destination is changed to the empty paper receiving tray (S110). When there are multiple empty paper receiving trays having the same face direction as that of the paper discharge destination full of paper, the paper discharge destination is determined according to the predetermined priorities. For example, the paper receiving trays are prioritized in descending order of maximum paper discharge capacity thereof.

By continuously discharging paper to the changed paper discharge destination, the printing process including the paper feed, image formation, and paper discharge is taken over (S103). As described above, in this embodiment, the paper discharge destination which takes over the receiving of discharged sheets is set depending on the availability of the trays at the time when the paper discharge destination becomes full. This makes it possible to again use the paper receiving tray which is once full of paper as the paper discharge destination.

FIGS. 10( a) to 10(e) are views schematically showing setting of the paper discharge destination by the above-described paper discharge control. Herein, to make it easy to understand, it is assumed that the printer 10 includes, as the face-up paper receiving trays, the two first and second face-up paper receiving trays. It is further assumed that the continuous printing is set; the paper discharge destination is set to the first face-up paper receiving tray at the start of printing; and every paper receiving tray is empty at the start of printing.

When printing using the first face-up paper receiving tray as the paper discharge destination progresses, and as shown in FIG. 10( a), the tray full detection sensor of the first face-up paper receiving tray detects that the first face-up paper receiving tray is full, the tray empty detection sensor of the second face-up paper receiving tray detects that the second face-up paper receiving tray is empty.

Since the second face-up paper receiving tray has the same face direction as that of the first face-up paper receiving tray, the paper discharge is taken over by the second face-up paper receiving tray to continue printing, as shown in FIG. 10( b). It is assumed that as shown in FIG. 10( c), all of the paper stacked on the first face-up paper receiving tray is removed by the user during paper discharge to the second face-up receiving tray.

When the printing further progresses and the tray full detection sensor of the second face-up paper receiving tray set as the paper discharge destination detects that the second face-up paper receiving tray is full as shown in FIG. 10( d), the tray empty detection sensor of the first face-up paper receiving tray detects that the first face-up paper receiving tray is empty at that time. Specifically, the first face-up paper receiving tray is full of paper at the time shown in FIG. 10( a), but the sheets thereon are removed at the time shown in FIG. 10( c). Accordingly, the first face-up paper receiving tray can be used as the paper discharge destination at the time shown in FIG. 10( d). Herein, when discharged sheets are returned to the first face-up paper receiving tray after once removed, the first face-up paper receiving tray cannot be judged empty at that time.

The first face-up paper receiving tray has the same face direction as that of the second face-up paper receiving tray. Accordingly, the paper discharge is taken over by the first face-up paper receiving tray as shown in FIG. 10( e) to continue printing. The continuous printing can be executed in this manner.

The printer with a plurality of paper receiving trays and the paper discharge control method for the same according to the embodiment of the present invention have been described above. However, the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Moreover, the effects described in the embodiment of the present invention are only a list of optimum effects achieved by the present invention. Hence, the effects of the present invention are not limited to those described in the embodiment of the present invention. 

1. A printer comprising: a plurality of paper receiving trays configured to receive discharged sheets; a tray full detection sensor configured to detect that an amount of discharged sheets stacked on the respective paper receiving trays reaches a respective predetermined amount; a tray empty detection sensor configured to detect that no discharged sheets are stacked on the respective paper receiving trays; and a paper discharge control unit configured to, when the tray full detection sensor detects that an amount of discharged sheets stacked on a first paper receiving tray used as a current paper discharge destination reaches the predetermined amount during printing, perform continuous paper discharge to continue printing by changing the paper discharge destination from the first paper receiving tray to a second paper receiving tray that the tray empty detection sensor detects as having no discharged sheets stacked thereon at a time of the detection of the first paper receiving tray and that receives discharged sheets with printed surfaces facing a same direction as that of the first paper receiving tray.
 2. The printer according to claim 1, wherein the paper discharge control unit temporarily stops printing without changing the paper discharge destination when the second paper receiving tray does not exist.
 3. The printer according to claim 1, further comprising: a print setting acquisition unit configured to acquire a print setting including a setting of a paper discharge destination and a selection as to whether or not to perform continuous paper discharge, wherein the paper discharge control unit determines, as a paper discharge destination at start of printing, a paper receiving tray belonging to a group having a larger number of paper receiving trays that receive discharged sheets with printed surfaces facing a same direction, when the print setting acquired by the print setting acquisition unit indicates that no paper receiving tray is set as a paper discharge destination and that performance of continuous paper discharge is selected.
 4. The printer according to claim 2, further comprising: a print setting acquisition unit configured to acquire a print setting including a setting of a paper discharge destination and a selection as to whether or not to perform continuous paper discharge, wherein the paper discharge control unit determines, as a paper discharge destination at start of printing, a paper receiving tray belonging to a group having a larger number of paper receiving trays that receive discharged sheets with printed surfaces facing a same direction, when the print setting acquired by the print setting acquisition unit indicates that no paper receiving tray is set as a paper discharge destination and that performance of continuous paper discharge is selected.
 5. The printer according to claim 1, wherein the paper discharge control unit performs continuous paper discharge to continue printing by changing the paper discharge destination from the second paper receiving tray to the first paper receiving tray when the tray full detection sensor detects that an amount of discharged sheets stacked on the second paper receiving tray used as a current paper discharge destination reaches the predetermined amount and also when the tray empty detection sensor detects that no discharged sheets are stacked on the first paper receiving tray at a time of the detection of the second paper receiving tray during printing after the paper discharge control unit changes the paper discharge destination from the first paper receiving tray to the second paper receiving tray.
 6. The printer according to claim 2, wherein the paper discharge control unit performs continuous paper discharge to continue printing by changing the paper discharge destination from the second paper receiving tray to the first paper receiving tray when the tray full detection sensor detects that an amount of discharged sheets stacked on the second paper receiving tray used as a current paper discharge destination reaches the predetermined amount and also when the tray empty detection sensor detects that no discharged sheets are stacked on the first paper receiving tray at a time of the detection of the second paper receiving tray during printing after the paper discharge control unit changes the paper discharge destination from the first paper receiving tray to the second paper receiving tray.
 7. The printer according to claim 3, wherein the paper discharge control unit performs continuous paper discharge to continue printing by changing the paper discharge destination from the second paper receiving tray to the first paper receiving tray when the tray full detection sensor detects that an amount of discharged sheets stacked on the second paper receiving tray used as a current paper discharge destination reaches the predetermined amount and also when the tray empty detection sensor detects that no discharged sheets are stacked on the first paper receiving tray at a time of the detection of the second paper receiving tray during printing after the paper discharge control unit changes the paper discharge destination from the first paper receiving tray to the second paper receiving tray.
 8. A method for controlling paper discharge in a printer including a plurality of paper receiving trays, the method comprising: detecting that an amount of discharged sheets stacked on a first one of the paper receiving trays used as a paper discharge destination reaches a predetermined amount during printing; and performing continuous paper discharge to continue printing by changing the paper discharge destination to a second one of the paper receiving trays that is detected as having no discharged sheet stacked thereon at the time of the detection of the first paper receiving tray and is configured to have discharged sheets stacked with printed surfaces facing the same direction as that of the first paper receiving tray.
 9. The method for controlling paper discharge according to claim 8, further comprising: temporarily stopping printing without changing the paper discharge destination when the second paper receiving tray does not exist.
 10. The method for controlling paper discharge according to claim 8, further comprising: acquiring a print setting including a setting of a paper discharge destination and a selection as to whether or not to perform continuous paper discharge, before starting printing; and determining, as a paper discharge destination at start of printing, a paper receiving tray belonging to a group having a larger number of paper receiving trays that receive discharged sheets with printed surfaces facing a same direction, when the acquired print setting indicates that no paper receiving tray is set as a paper discharge destination and that performance of continuous paper discharge is selected.
 11. The method for controlling paper discharge according to claim 9, further comprising: acquiring a print setting including a setting of a paper discharge destination and a selection as to whether or not to perform continuous paper discharge, before starting printing; and determining, as a paper discharge destination at start of printing, a paper receiving tray belonging to a group having a larger number of paper receiving trays that receive discharged sheets with printed surfaces facing a same direction, when the acquired print setting indicates that no paper receiving tray is set as a paper discharge destination and that performance of continuous paper discharge is selected.
 12. The method for controlling paper discharge according to claim 8, further comprising: performing continuous paper discharge to continue printing by changing the paper discharge destination from the second paper receiving tray to the first paper receiving tray when detecting that an amount of discharged sheets stacked on the second receiving tray used as a current paper discharge destination reaches the predetermined amount and also when detecting that no discharged sheets are stacked on the first paper receiving tray at a time of the detection of the second paper receiving tray during printing after changing the paper discharge destination from the first paper receiving tray to the second paper receiving tray.
 13. The method for controlling paper discharge according to claim 9, further comprising: performing continuous paper discharge to continue printing by changing the paper discharge destination from the second paper receiving tray to the first paper receiving tray when detecting that an amount of discharged sheets stacked on the second receiving tray used as a current paper discharge destination reaches the predetermined amount and also when detecting that no discharged sheets are stacked on the first paper receiving tray at a time of the detection of the second paper receiving tray during printing after changing the paper discharge destination from the first paper receiving tray to the second paper receiving tray.
 14. The method for controlling paper discharge according to claim 10, further comprising: performing continuous paper discharge to continue printing by changing the paper discharge destination from the second paper receiving tray to the first paper receiving tray when detecting that an amount of discharged sheets stacked on the second receiving tray used as a current paper discharge destination reaches the predetermined amount and also when detecting that no discharged sheets are stacked on the first paper receiving tray at a time of the detection of the second paper receiving tray during printing after changing the paper discharge destination from the first paper receiving tray to the second paper receiving tray. 